Thin Film Transistor Liquid Crystal Displayers (TFT-LCDs) are display devices in which the rotation degree of liquid crystal molecules are changed by utilizing a change in intensity of an electric field applied to a liquid crystal layer, so that an intensity of the transmitted light is controlled to display images. Generally, a TFT-LCD display panel may include a backlight module, a polarizer, a color filter substrate, a TFT array substrate and a liquid crystal molecule layer located between the color filter substrate and the TFT array substrate.
In recent years, TFT-LCDs have been developed swiftly. For purpose of improving the display quality, TFT-LCDs use a driving circuit operated at a higher frequency, as dimensions thereof are increased constantly and resolutions thereof are enhanced constantly. In this case, TFT-LCDs have a shorter time for charging, and thus need a semiconductor material with a high mobility. In addition, delay of image signals also becomes one of key factors in restraining the display effect of TFT-LCDs having large size and high resolution, and therefore, metal material Cu with a low resistance is usually used in the TFT array substrate for forming data lines.
A process for manufacturing the TFT array substrate in the prior art may comprise: forming gate lines, gate electrodes, a gate insulating layer and a semiconductor active layer on a substrate sequentially; in order to prevent metal materials from polluting the semiconductor active layer upon forming source electrodes and drain electrodes subsequently, forming a protection layer with via holes on the semiconductor active layer; and forming the source electrodes and the drain electrodes which are connected to the semiconductor active layer through the via holes on the protection layer. In this way, the number of patterning processes is increased by one due to the formation of the protection layer, so that the production efficiency of the TFT array substrate is decreased and the production cost is increased.